I came to Turkey for volunteering 2 years ago, which turned out one of the best experiences, I volunteered for 4 months in 2 different places , and now I am working in one of them
first place was an adventure camp and 2nd was an organic farm, they were both A great place .
after looking up online for very long time for any volunteering position in Turkey I came across workaway.info.
The website isn't free you have to pay $29/year To contact any host.
also Note answers or acceptance from host isn't guarantee, 80% are negative replies or no reply at all, So you have to be patient.

Most hosts charges no money and they offer Accommodation and many they offer free Food as well in exchange of 4 to 6 hours volunteering a day 5 Days a week.
If you are in Turkey and don't have paid account in workaway I can recommend you some places to volunteer in which they reply fast. just pm me