Can i use my Iphone 4s with Metro PCS?

OK,
so my dad found an Iphone 4S at the park a week ago. The person just left it on the train. So my dad brought it home and gave it to me. I took out the sim card and restored it with a new passsword and updated it. Now, i want to connect it to metro Pcs with a sim card or whatever. Is it possible? The phone he found was from Sprint.

Yes you can just take out the sprint sim card and put in your metro pcs sim card and you monthly plan will be with metro pcs

Or, you could just be honest, and try to find the owner. If you lost your phone, would you want someone to take it as their own? How to find the owner… How about taking it to the phone service they have (Verizon etc.) who can look up the name and return it to them?