There is no AND/OR operator. It is as follows:
By default, all entries will be processed using AND operator.
If you search for: guigsims holenextdoor
you are making a search for torrents containing both the terms guigsims AND holenextdoor.
If you want to search for either one OR the other, do (guigsims)(holenextdoor)
with each string between parenthesis and no space between them.
If you want to search for an exact phrase, use quotations, like "guigsims guilherme oliveira"
If you want to exclude a word use: guigsims -guilherme
or to exclude an exact phrase: guigsims -"guilherme oliveira"
.
Hopefully this was helpful.