Guitarists can play notes that fall between the keys on a piano. They do this mainly by bending strings with their fretting hands, or using slides or whammy bars. You can't play the same notes on a piano, though you can play them on lots of other instruments, including electronic keyboards with pitch bend controls. So you can't don't assume that guitar music can be accurately emulated with piano chords.

Western music with pitch-bent notes is typically blues music. If the music you're trying to play has a blues flavour, you might be able to produce a sound with a similar flavour on a piano. For instance, you might play the F# as a grace note approaching the G, or you might play both notes together in a short stab. This won't sound like the guitar, but it might work as a substitute. If you want to know more about these sorts of techniques you should study blues piano.