I agree with DIKI - ditch that sheet music, and learn to play those songs by ear. You will be amazed at what you can do with just a bit of creativity while playing an arranger keyboard. Granted, the sheets will help you in learning a song that you have never played, but if you have to have something in front of you, a chord chart or lyrics with the chord changes over the words is really the best way to go, IMO. At least, it worked for me.

Good luck,

Gary