You can’t, fee waivers are only for students in the US, or occasionally US citizens abroad: SAT Fee Waivers
If you really cannot afford the SAT fee, you must be hoping for an incredible scholarship at an American university (if you do not think you will get a scholarship, I don’t know how you will pay for the tuition). You may have a chance if you are an exceptional candidate, but this would be incredibly rare. If you do believe that you are a 1 in a million student, contact the school that you want to go to directly. It would also be worth seeking some advice from a teacher or counsellor about how to navigate the process - it sounds like you need some advice that is more specific to your situation.
Hope that helps. Feel free to ask again if you need more info.
Source : https://www.quora.com/How-can-a-Pakistani-student-get-a-fee-waiver-for-SAT