You can directly pass object map for http client or create HttpHeaders class to supply the headers.
constructor(private _http: HttpClient) {} this._http.get('someUrl',{ headers: {'header1':'value1','header2':'value2'} }); (or) let headers = new HttpHeaders().set('header1', headerValue1); // create header object headers = headers.append('header2', headerValue2); // add a new header, creating a new object headers = headers.append('header3', headerValue3); // add another header let params = new HttpParams().set('param1', value1); // create params object params = params.append('param2', value2); // add a new param, creating a new object params = params.append('param3', value3); // add another param return this._http.get<any[]>('someUrl', { headers: headers, params: params })