I would definitely rake the leaves on your lawn as retaining a thick, dense mat of leaves across your lawn can cause serious aesthetic and disease problems next spring. Remember, your lawn is still actively growing (heck, it's 70 degrees outside right now as I type this reply), so it makes very little sense to intentionally smother your cool-season grass lawn via the shade and weight of excess leaves -- rake them up, but don't feel compelled to rake up 100% of the leaves as that would be a fool's errand. I would suggest raking as many of the leaves as possible followed by an end of the year, high-mow to shred/mulch any residual leaves that always seem to blow onto your lawn -- shredded leaves have greater surface area and will decompose much faster than intact leaves.
Essentially, the negative impacts of smothering your lawn far outweigh the minimal "fertilizer" effect you will realize based upon recently senesced leaves on turf grass.
Thanks for your question!