Given a messy JSON payload from a laboratory API, write a Python script to flatten the data and extract specific biomarker values. Implement extract_biomarkers(payload, biomarkers), where payload is a nested dictionary containing dictionaries and lists. A biomarker record contains biomarker or name, plus value or result.value; key matching is case-insensitive. Return a dictionary keyed by the requested names, with lists of values in traversal order. Include every requested key, using an empty list when no value is found.
def extract_biomarkers(payload, biomarkers):