Make identity attribute searchable via SCIM API Call

How do I make an existing identity attribute searchable via the SCIM API Calls ? I want to pass it like this:

https://HOST/identityiq/scim/v2/Users?Accept=application/json&filter=MYATTR eq 548378
OR
https://HOST/identityiq/scim/v2/Users?filter=urn:ietf:params:scim:schemas:core:2.0:User:MYATTR eq 548378