How to create dynamic nested aggregations query in elastic search.net based on multiple fields

How to create dynamic nested aggregations query in Elastic search.net based on multiple fields.

These are my fields.

1. keyword 1
2. keyword 2
3. keyword 3

This is my static query.

ISearchResponse<T> response = client.Search<T>
                (
                    s => s
                    .Index(indexName)
                    .Type(docType)
                    .Size(0)
                    .RequestConfiguration(r => r.DisableDirectStreaming())
                    .Aggregations
                    (
                        a => a.Terms("result_by_keyword_1", t => t.Field("keyword 1").Missing("N/A").Size(10000)
                        .Aggregations
                        (
                            ag => ag.Terms("result_by_keyword_2", tg => tg.Field("keyword 2").Missing("N/A").Size(10000)
                            .Aggregations
                            (
                                agf => agf.Terms("result_by_keyword_3", tfg => tfg.Field("keyword 3").Missing("N/A").Size(10000))
                            ))
                        ))
                    )
                 );

I need to access data like this:

foreach (var bucket in response.Aggs.Terms("result_by_keyword_1").Buckets)
            {
                foreach (var innerBucket in bucket.Terms("result_by_keyword_2").Buckets)
                {
                    foreach (var innerBucket1 in innerBucket.Terms("result_by_keyword_3").Buckets)
                    {
                        AggregateData aggData = new AggregateData();
                        aggData.keyword1= bucket.Key;
                        aggData.keyword2= innerBucket.Key;
                        aggData.keyword3= innerBucket1.Key;
                        aggData.recordcount = innerBucket1.DocCount;
                        results.Add(aggData);
                    }
                }
            }

Problems are : Actually I want to create a dynamic query based on multiple fields. here I have 3 fields but it may more than 3 fields.so based on fields count I want to nested aggeration in elastic search in .net.

Thanks in advance.