How to replace a specific value in a MySQL row if the word is exist?

Question

How can I replace a specific value in MySQL if it's exist?

I have a servers table in that table I have an opts row the row's value is:

+set net_port 28112 +set rcon_password asd +set fs_game mods/pml220 +set sv_punkbuster 1 +exec server.cfg +map_rotate

I don't want to update the whole row with update statemet just want to replace the +set fs_game mods/pml220 to +set fs_game mods/test

I tried with the REPLACE statement but to be honest I don't really understand what is going on, lol.

SELECT opts,
  REPLACE( opts, '+set fs_game mods/pml220', '+set fs_game mods/test' ) as opts
FROM servers
WHERE srvid>2709;