CRJ-900 Captain reported asking for a heading to avoid wake turbulence on descent into LGA; but they then received an RA from helicopter traffic.

Narrative

We were coming into LGA at night and we got descended from 10 to 8k. The aircraft in front of of us either didn't get the descent or was slow to descend and we started getting bounced around from their wake. When we asked to be vectored out of his wake they gave us a 90dg turn and seemed like they were vectoring us off the arrival and were putting us in the back of the arrival line. So; we clarified and said we just need vectored out of the wake. The controller corrected and gave us a new heading. The new heading took us closer to the city than the traffic ahead of us. We got a another descent from 8 to 4k and we were advised of a helicopter at our 1 o'clock at 4.5k circling over the city. I don't know if it was cause we were on a different heading than the plane in front but the vector seemed to be taking us close but we had them in sight. The helicopter looked to be turning away from us but circled back to us. Frequency was busy and we couldn't ask for anything so I (pilot flying (PF)) turned a few more degrees away from the traffic trying to avoid a RA. We received an RA so I kicked off the Autopilot followed the RA guidance and First Officer (FO) told ATC we were responding to an RA. Once maneuver was complete we turned Autopilot back on and continued being vectored for the approach.