Basement window with cinderblock. Do I need to fill cinderblock?
Weep holes are supposed to be outside of the facade or over a downward sloping sill. Windows are supposed to sit in a frame. Caulk will not seal the window for long in your situation. Also, be aware that cinder block is porous, so if you just put a little around the edges, water will go right around it through the cinder block.

Basically the problem is that you have no frame, so you need to get a smaller window and build a frame, or chip out enough of the cinder block that you can fit a proper liner and sill around the window.