solr search in multiple fields
You could use Search Api  Module


  This module provides a framework for easily creating searches on any
  entity known to Drupal, using any kind of search engine. For site
  administrators, it is a great alternative to other search solutions,
  since it already incorporates facetting support and the ability to use
  the Views module for displaying search results, filters, etc. Also,
  with the Apache Solr integration, a high-performance search engine is
  available for this module.


Using It you could create index for the field you choose!!