using -LOP correctly

I would like a URL that makes multiple find requests where each request has multiple fields involved.

In other words, I would like a find that results in:

NameField=Mary and CategoryField=Teacher OR

NameField=Steve and CategoryField=Student

This would result in all records where Mary is a teacher or Steve is a student.

I would have thought that the URL would be:

...&-Lop=AND&NameField=Mary&CategoryField=Teacher&-Lop=OR&NameField=Steve&CategoryField=Student&-find

Of course the last -Lop takes over and this resulted in all records where NameField=Mary plus all records where NameField=Steve plus all records where CategoryField=Teacher plus all records where CategoryField=Student. (ultimately 4 find requests with data in only 1 field each)

How do I create a URL that only has 2 find requests, where each request has data in two fields?

Thanks