Currently this can be achieved using regex notation ...
You have to choose "matches" instead of "contains" and you can use the "OR" regex operator |
Origin is hub
probe matches cmd|process
message matches threshold|stopped
this would match messages which contain the word "threshold" or "stopped" -- it does not require a full/exact match.
'OR' operator will most likely be added in a future release to make it easier/more intuitive.