AutcompleteSearch.cs

public SearchResults<SearchResultItem> Search(ISearchIndex index, string searchQuery)
{
	using (var context = index.CreateSearchContext())
	{
		var dataQuery = context.GetQueryable<SearchResultItem>()
                                       .Where(i => i["non_ngram_field"] == searchQuery);
		return dataQuery.GetResults(context, CreateQuery(searchQuery));
	}
}

protected Func<Query, Query> CreateQuery(string term)
{
	Func<Query, Query> query = luceneQuery =>
	{
		var queryParser = new QueryParser(Version.LUCENE_30, "smartsearch",
			new StandardAnalyzer(Version.LUCENE_30));
		var smartSearchQuery = queryParser.Parse(term);

		var booleanQuery = new BooleanQuery();
		booleanQuery.Add(luceneQuery, Occur.SHOULD);
		booleanQuery.Add(smartSearchQuery, Occur.SHOULD);

		return booleanQuery;
	};

	return query;
}