如何在elasticsearch客户端搜索功能中只获取'_source‘字段？

from elasticsearch import Elasticsearch

# 创建一个Elasticsearch客户端实例
es = Elasticsearch()

# 搜索请求
search_body = {
    "query": {
        "match": {
            "title": "关键词"
        }
    },
    "_source": ["field1", "field2"]  # 指定需要返回的字段
}

# 发送搜索请求
response = es.search(index="your_index", body=search_body)

# 处理搜索结果
for hit in response["hits"]["hits"]:
    source = hit["_source"]
    # 处理返回的字段数据
    field1_value = source.get("field1")
    field2_value = source.get("field2")
    # 其他操作...