OR queries throw 400 error

Hi
I'm writing a custom filter for the search_api_solr that uses the OR #conjunction.
With the OR #conjunction the query type is switched to standard (as expected) but the generated query (when run against solr directly) results in this error.

no field name specified in query and no defaultSearchField defined in schema.xml

The field names are in the query, however they've been supplemented with the boost figures (ie ^1.0) which are for the dismax query type.
Removing the boost figures from the field names fixes the issues. The attached patch contains the fix.

Lee