I wouldn't want to be the bearer of bad news but it's nearly impossible to live a life without an extra job besides being a musician. All the (Turkish) people you see on stage or on YouTube etc. have a "real" job or they had before they really made it as a musician.
Most of the time, people like you try to do that while working in a coffee shop, etc. unless they haven't got a job as an officer, engineer, or any other steady work. But you want a contract and probably no professional musician who can work with you would offer that just because of your talent.
So if you really believe yourself look for any job that covers your rent and food in İstanbul. Then you can create your own network and if you're lucky, perform your talent directly to the professionals. Still keep this in your mind all the time, the musicians or bands that can make a living with only music achieve this situation because of their persistent works and steady members. So, you can either create your own path or wait for your turn to join that kind of band.