In cloud Electronic Medical Records (EMRs), a user’s medical records typically comprise various types of health-related sensitive data. When data ownership needs to be transferred, it is preferred to transfer the required data to target users, instead of transferring the entire records. Existing protocols cannot adequately address this issue. Therefore, we leverage the searchable encryption and propose a fine-grained ownership transfer protocol. Specifically, users in our protocol determine data blocks for ownership transfer based on keywords. Additionally, our protocol is designed for single-owner to multi-owner scenario, it is achieved by leveraging characteristics of threshold signatures and multi-signatures. The employment of threshold signatures and multi-signatures realizes flexible and less resource-intensive ownership transfer. Furthermore, we experimentally analyse the performance of our protocol, and compare it with relevant protocols. According to the comparisons, our protocol has more features with moderate resource consumptions.