title: Query to see if a field contains a string using Query DSL
body: <p>I am trying to filter Kibana for a field that contains the string "pH".  The field is called <code>extra.monitor_value_name</code>.  Examples of potential values are <code>Temperature_ABC01</code>, <code>DO_ABC01</code>, or <code>pH_ABC01</code>.</p>
  
  <p>Kibana's Elasticsearch Query DSL does not seem to have a "contains string" so I need to custom make a query.</p>
  
  <p>I am new to Query DSL, can you help me create the query?</p>
  
  <p>Also, is it proper to call it Query DSL?  I'm not even sure of proper wording.</p>