Have not tried olive but I have done lots of cuttings. I would say that right now would be an excellent time. Select branches that grew fast, and all this last year. (one year old wood.) I like to prepare the cutting before I actually cut it. In this case, remove all but 3 to 5 leaves, leaving only a very few at the tip. Do this a day or 2 before cutting. This way the tree can provide the sap to help heal the leaf breaks, instead of taking strength from the new cutting. If you can find some really vigorous growth that grew all last year, (all in one year, usually a lighter or more green color) you can do the cuttings without leaves at the tip and will probably have better success. Nice thick stem branches are the best. Take cuttings about 8 inches long. Be sure that you will have at least 2 (3 is better) nodes below ground and at least 2 above ground. Use a rooting hormone, like Rotenone (not sure I spelled that right) and lightly powder the part that will go in the ground, about 4 inches worth, with at least 2 nodes. Plant in good potting mix. I like to plant at a little angle, not sticking straight up, as this seems to give the cutting a better rooting start. Give a warm sunny place, making sure the potting soil does not get soggy or dry out. When days are a little too hot, sprinkle with cool water to keep them from scorching. Let us know how it turns out, and good luck.

there is a way to post pictures but i dont know how i am new to the site i also dont know much about olives other than autumn olives so i am afraid im not going to be able to help very much if you do figure out how to post pictures i think there is a forum section dedicated to plant identification

While olives may be quite drought tolerant when established, they DO appreciate watering during very dry spells. It is suggested to water 1-2 times per month in summer, with a slow deep soaking (not a sprinkler) - no water in winter. A soaker hose or drip irrigation are very efficient methods of slow water delivery. Flowering and fruit production depends heavily on proper pruning practices. Production is heaviest on one year old wood and you want the tree canopy to be vase shaped, open and airy. There is an old Italian saying regarding olives that you want to prune them so that a "swallow can fly through them", meaning that light and air are allowed to penetrate into the center of the tree. This link offer good pruning tips and a helpful video. What is causing the dieback is impossible to determine from just the photos. If you resided in this country, I'd suggest taking in photos and samples to a plant pathology specialist (via extension service) for diagnosis but not sure what similar services you may have in Turkey. This link provides an excellent overview of olive care and cultural requirements plus outlines a number of disease pathogens - some quite serious - that can affect olives in a manner similar to what you are seeing. Regardless, any dead portions should be removed but until you are able to ascertain exactly what is causing the problem, I would suggest sterilizing any pruning equipment between cuts. But my first order of business would be to locate someone local to you to properly diagnose any possible disease issues.

Yes, we may be able to help if we can view the thing somehow.