How do I get the spoken words between a point in the sentence?

I’m using Kaldi and would like to search and play a song on spotify (using spotcast)

My sentence would be something like:

Play (I_DO_NOT_KNOW_WHAT_GOES_HERE){song_name} on Spotify

Is there a standard way of gathering any words spoken between “play” and “on”? Or do get an entire slot filled with all the english words?