I having an issue passing a URL value into the header.

I have added this code:

    CustomerFieldscheduling.CFSPartnerSlotsServiceImplPort cfsPort = new CustomerFieldscheduling.CFSPartnerSlotsServiceImplPort();
            
            Blob headerValue = Blob.valueOf('LOGIN' + ':' + 'LOGINPWD');
            String authorizationHeader = 'Basic ' +EncodingUtil.base64Encode(headerValue);
                String sURL = 'https:/testURL';
                System.debug('***authorizationHeader***'+authorizationHeader);
                cfsPort.inputHttpHeaders_x = new Map<String,String>();
                cfsPort.inputHttpHeaders_x.put('URL',sURL);        
                cfsPort.inputHttpHeaders_x.put('Authorization',authorizationHeader);

When i tried to invoked the webservice, able to connect to the operation that i need to call but getting the error of the URL not being part of the request that i sent

    <env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <env:Header/>
    </env:Header><env:Body>....</env:Body>

the web service is expecting a request in this format

    <env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <env:Header>
    <URL>https:/testURL</URL>
    </env:Header><env:Body>

Can you please share idea on how i could attain the said format.