If I understood, you want to use the value of ${address} to query only on the address and region attributes.
In that case, based on the "complex" query string example at http://grails.org/Searchable+Plugin+-+Searching+-+String+Queries, your query string could be:
"+(address:${address} OR region:${address}) price:[100 TO 1000]"
- Matches must have a ${address} value for address or a ${address} value for region, and have a value from 100 to 1000 for price.
Note: your input variable has the same name of an entity attribute, "address", wich can cause some confusion when trying to understand query strings using them both. Though not needed, you might want to change that, for easier readable query strings.