Set default search fields in Apache Solr

I am trying to Implement Apache Solr search through SolrNet library.So far I have managed to run an instance of Solr in my machine and make some queries based on specific fields. My code to do it looks like this

   var solr = ServiceLocator.Current.GetInstance<ISolrOperations<Product>>();
   var results = solr.Query(new SolrQueryByField("id", "SP2514N"));

This one works fine now,But I would like to make queries with out specifying a field , So that when I enter a search key word solr will look in to the all fields available and return a result.I have Found the code to make it in SolrNet library from here

        var solr = ServiceLocator.Current.GetInstance<ISolrOperations<Product>>();
        var results = solr.Query(new SolrQuery("SP2514N"));

But this never worked,When I drilled down to bottom ,I found that I need to set default search fields in Solr instance so that Solr will search that fields when nothing else is selected(This is how i understood it I am not sure about this). So I went to set default fields in Solr ,I took Solrconfig.XML and edited it like this

    <requestHandler name="/query" class="solr.SearchHandler" default="true">
     <lst name="defaults">
       <str name="echoParams">explicit</str>
       <str name="wt">json</str>
       <str name="indent">true</str>
       <str name="df">text</str>
       <str name="df">id</str>
     </lst>
  </requestHandler>

[just added <str name="df">id</str> this field as extra].But this too never helped And I am stuck ,Can any one tell me How I could set default search field in Solr correctly?Or am i doing any thing else wrong? I have Uploaded My Solrconfig file here

I do not know about SolrNet library, but to make a default field for search you need to define DefaultSearchField in schema.xml i.e. <defaultSearchField>FieldName</defaultSearchField>.

You can find this file @ <SOLR_HOME>\apache-solr-3.6.0\example\example-DIH\solr\testsyndrome\conf\schema.xml

I hope that's what you are looking for.