I agree with Dogdaze on bleeding the clutch first. Always try the simple and cheap fixes before jumping into the expensive ones. If you had not been having clutch issues for some significant time prior to this, I would say that it's unlikely the clutch friction disks or steels need to be replaced.
What year bike & how many miles?
From your description, it would fit with the clutch not being fully disengaged when you pull the lever. That could be as simple as air in the line, a bad master cylinder, (or dirty one), or a bad slave cylinder. There are other things, but they are far less common and less likely to have occurred. pull the master cylinder cover on the left bar, suck out the fluid, clean carefully with tissue/q-tips and fill with new Dot 4 brake fluid, then carefully bleed w/o sucking air into the system, keeping the reservoir topped off. A pain because it's so small. When you get fresh fluid out the bottom, button it up and see what the lever feels like. If it feels soft or "funny", open it back up and either re-bleed, or tie the lever to the bar, use a screwdriver handle or similar to gently tap the fittings and line from the bottom to the top, moving along slowly, then leave the cover off and lever tied to the bar over night. Button it up the next morning and see what it feels like. If good/normal, fire the bike up in neutral and on the center stand and see if the rear wheel spins while in neutral with the clutch lever pulled in. It may spin a little and be ok, but you should be able to stop it easily with some pressure on the wheel/tire.
If it's clearly moving along try shifting into 1st, releasing the clutch lever and letting the wheel spin up at idle, then pull the clutch lever in and see what happens. Hopefully the wheel will noticeably slow down, which is a good sign. If it doesn't, either the clutch plates are sticking together, or the clutch is still not fully disengaging and other things need to be investigated.
IF you check and rule out these issues, then I would move on to pulling the clutch cover, (the gasket usually does not tear and can be re-used), and at least visually inspecting for something out of place. (Note that the bolts should be tightened in a specific sequence to avoid a leaky gasket or stress to the cover.)
You can remove the clutch plates/friction disks, (except the last one), w/o removing the nut that holds the clutch boss in place. If you remove the plates, make a paint mark, (nail polish works well), on the outer clutch plate and the clutch hub so you put them back the same way. The other plates are not as critical, but you will see there is a right and wrong way to install them that becomes apparent when you do it. Things don't fit in if you're off a notch. I would leave pulling and examining the clutch plates for last, as they are rarely an issue unless you have very high mileage. Mine looked nearly new at 85k miles or so when I upgraded my '12 to a '14 Clutch hub.
