Search on multiple items in one field?

Hello,
I would like to search like this in advanced search.
Table student

[indent] studentname

studentaddress

studentlevel

etc.

[/indent]

Lets say I have following student levels. L1, L2, L3, L4, M1, M2, M3, H1, H2, H3 etc.
Now I want to search in advanced search for all students with level ( L1 or M2 or H3 )
How can I create this in advanced search?
Thank you,
Regards,
Johan