core/src/main/java/com/orientechnologies/orient/core/sql/operator/OQueryOperatorContainsText.java
@Override
  public Object evaluateRecord(final OIdentifiable iRecord, ODocument iCurrentResult, final OSQLFilterCondition iCondition,
      final Object iLeft, final Object iRight, OCommandContext iContext, final ODocumentSerializer serializer) {
    if (iLeft == null || iRight == null)
      return false;

    return iLeft.toString().indexOf(iRight.toString()) > -1;
  }
@Override
  public Object evaluateRecord(final OIdentifiable iRecord, ODocument iCurrentResult, final OSQLFilterCondition iCondition,
      final Object iLeft, final Object iRight, OCommandContext iContext, final ODocumentSerializer serializer) {
    if (iLeft == null || iRight == null)
      return false;

    return iLeft.toString().indexOf(iRight.toString()) > -1;
  }
This is executed on non-indexed fields.