We cannot answer treaty questions here.
However, as a resident alien, you need to declare your worldwide income no matter where it is earned or received. You can use foreign tax credit section in TurboTax to help offset double taxation.
You can enter the foreign income in the foreign tax credit section of TurboTax.
Under Deductions and Credits, choose I'll choose what to work on
Scroll down and you will see Foreign Tax Credit under Estimates and Other Taxes Paid
Go through the first number of screens about foreign taxes on interest, etc.
You will come to a screen that asks what category of income you need to report, Click General Catagory Income
Pick Turkey as the country. On the next screen you can enter a description (Wages) and amount of gross income he earned in Turkey.