Set filter in Langchain Self-Query Retriever

Question

I use the Self-Query Retriever from langchain lib and want to set the filter to "in", because my attribute is string of keywords (comma-separated).

I create a retriever:

from langchain.retrievers.self_query.base import SelfQueryRetriever

SQretriever = SelfQueryRetriever.from_llm(
    llm,
    vectorstore,
    document_content_description,
    metadata_field_info,
    verbose = True,
    k=5,
)

And then I want to get the documents:

SQretriever.get_relevant_documents("What color has the sky?")

INFO:langchain.retrievers.self_query.base:Generated Query: query='blue' filter=Comparison(comparator=<Comparator.EQ: 'eq'>, attribute='news_keywords', value='blue') limit=None

The logging shows, that the retriever use an equal comparator and I want to use an in comparator. How can I set it?