Both ID3v2 and Vorbis comment (native tagging format for MP3 and Ogg Vorbis / FLAC respectively) have multiple tags to store such information. That's how I do it:
<Performer tag> Contains vocalists, chorus performers, instrument performers and so on in multiline format
<Composer tag> Contains composer (!) information under the condition that arranger information exists, also the lyricist info and possibly who translated the lyrics is found here -- again in multiline style
<Artist tag> Contains arranger information if both composer and arranger info are known (even if both are the same). If that's not the case then the composer is entered here. So if the booklet only provides composer info then this ends up here
Example: Take track 03 from Kanon OST (
http://vgmdb.net/album/543)
<Artist tag> Kazuya Takase (I've)
<Composer tag> Key / Jun Maeda (Music and Lyrics)
<Performer tag> Ayana (Vocals)