>>In other words, use both criteria - the index and LIKE (as I also suggested originally).
>>
>>The index will be quick and then if you're looking for exact phrase, you filter the results with LIKE.
>
>I will have to benchmark that to make sure it doesn't deoptimized everything. Thanks for the suggestion

If you get the dataset, can you apply the extra condition in .NET side? Although you can also do it in SQL.

And may be you can apply LINQ on the result set.