Every word in a trigger or event is repreented by $1,$2,$3,... etc. If you would like bunched of words however, you can use the identifier, and a hyphen. Example:
Trigger for!request Some Song
In the event, you know !request to be $1, Some to be $2, and Song to be $3. If you wanted just the request (everything after !request) you could use $2- That means the second word, and onword. You can also do $2-3 which means words 2 through 3.
So to answer your question, use $3- in your request script. That will include everything past their first word.