You should not attempt to do that.
First of all, 3.5" drives use 12V in addition to 5V, which your case most likely can't provide.
But more importantly: If you want to recover data, the one thing you do NOT want ist to put your disk into any non-optimal working conditions. Not 100% clean and sufficient power might keep your disk sort of working but put an enormous strain on the drives motor speed controller. It might also be "just not enough" with your drive restarting, again making your recovery job harder and more risky.
A 3.5" case (or a "HDD docking station") is a few $/€ on e-Bay and will come with a dedicated power supply.