Adding stream_type=all as a parameter to /streams will return the stream object for live and playlists streams. There is a is_playlist boolean under the stream object which will indicate if it’s a playlist or not.
Ex: https://api.twitch.tv/kraken/streams/fishstix?stream_type=all
Possible values of stream_type appear to be all, playlist, or live and it seems to work on all the /streams endpoints.