How to make an or statement in a firebase realtime database

Question

I have a realtime database in firebase and have the following query

query(ref(database, 'message/'), orderByChild('ReceiverID'), equalTo("Username"))

But I want to create the following query

query(ref(database, 'message/'), orderByChild('ReceiverID'), equalTo("Username") or orderByChild('SenderID'), equalTo("Username"))