How do I include Form 1042-S with exemption code 16 (I'm a grad student) in TurboTax? I am a non-resident alien who qualified for the substantial presence test.

Yes. here is the reporting process.

To report the 1042-S 

1. Open your return in TurboTax 
2. Click on Wages & Income 
3. Scroll down to All Income
4. Scroll down to Less Common Income 
5. Scroll down to Miscellaneous Income, 1099-A, 1099-C 
6. Click start 
7. Scroll down to Other reportable income 
8. Answer yes and record this as 1042S income and then the amount.

To report the US tax paid:

1. With your return open
2. Click on Deductions & Credits
3. Scroll down to Estimates and Other Taxes Paid\
4. Click on Other Income Taxes
5. Scroll down Other Income Taxes
6. Click on Withholding not already entered on a W-2 or 1099