Request body should contain either ref_id or cust_ref_id.

If both ref_id and cust_ref_id are passed, then the system will match both fields for finding the update record.

If a matching record is not found, the update request would generate a 400-Bad Request.

The update request should contain at least one of the following fields. System will try to update all the fields passed in the request

phone: will be appended to existing phone numbers (if not already exists in the lead)
email: will be appended to existing emails (if not already exists in the lead)
owner: will modify the current owner (Sales Person) of the lead
lead_status: Should be valid lead status slug