The equipment you might suit you best might depend on whether the intent is to fiddle around at home, or to play live gigs.
There are MIDI keyboard controllers which merely send a MIDI signal to indicate which keys were pressed, and how hard, etc. There are hardware-based sound modules (Roland and others) that can be used with these, to create the desired noises that sound like a piano, organ, clav, horn, etc. There are similar software-based sound modules which can run on a PC (if you have one).
One thing to keep in mind is that if want to hear an amplified sound from a keyboard (other than via headphones), you will need a real keyboard amp, not a guitar amp, due to the wider frequency range and the unacceptability of distortion that keyboard sounds require. If this is just for home use, and you are already playing backing tracks through a home stereo, then this approach might still work out ok for such home-only usage.
There are MIDI keyboard controllers which merely send a MIDI signal to indicate which keys were pressed, and how hard, etc. There are hardware-based sound modules (Roland and others) that can be used with these, to create the desired noises that sound like a piano, organ, clav, horn, etc. There are similar software-based sound modules which can run on a PC (if you have one).
One thing to keep in mind is that if want to hear an amplified sound from a keyboard (other than via headphones), you will need a real keyboard amp, not a guitar amp, due to the wider frequency range and the unacceptability of distortion that keyboard sounds require. If this is just for home use, and you are already playing backing tracks through a home stereo, then this approach might still work out ok for such home-only usage.