ESQuery.cs

// Create a query where the result must match or contain the given query
// and the subset of properties and filters.
descriptor.Query(
    q => q.Bool(
            b => b.Must(
                    mu =>
                        mu.MultiMatch(
                            m => m.Fields(propertyExpressions) // Search within these properties or all.
                            .Query(searchTerm) // For this query
                            .Operator(Operator.Or))) // In any of the properties.
                    .Filter(filters))); // Further filter results.

I'm not sure if you've seen. but the elasticsearch-net-example repository has an example of filtering nuget packages by authors and tags

https://github.com/elastic/elasticsearch-net-example/blob/5.x-codecomplete-netcore-modifications/src/NuSearch.Web/Modules/Search/Search/SearchController.cs