Keywords are inclusive, so the more keywords you put in, the less lines you'll find.
You can specifically ask for a keyword to not exist by prefixing it with !.
For example, searching for "mouse !cheese milk" would find lines that contain both mouse and milk but not cheese.

[060314 16:42] 21b70, Peanut: wanted Tamarack X wanted! any contact info!

[060318 07:47] 7c5c4, Peanut: my baby takes the mornin train!