To search for the word "OR" (or other MATCH expression keywords), you have to quote them (double quotes are usually used for phrase searches, and are harmless for single words):
sqlite> select * from t where t match 'NOT OR';
Error: malformed MATCH expression: [NOT OR]
sqlite> select * from t where t match '"NOT" "OR"';
TO BE OR NOT TO BE
Searching for the word "or" works just fine, because match expression keywords are case sensitive; it might be easiest for you to use only lowercase search words:
sqlite> select * from t where t match 'not or';
TO BE OR NOT TO BE