Invoking PowerShell Script with Arguments from C#

I have a PowerShell script stored in a file. In Windows PowerShell, I execute the script as
.\MergeDocuments.ps1 "1.docx" "2.docx" "merge.docx"

I want to call the script from C#. Currently I am using Process.Start as follows which works perfectly:
Process.Start(POWERSHELL_PATH, string.Format("-File \"{0}\" {1} {2}", SCRIPT_PATH, string.Join(" ", filesToMerge), outputFilename));

I want to run it using Pipeline class, something like the below code but I don't know how to pass the arguments (keep in mind that I don't have named arguments, I am just using $args)

// create Powershell runspace
Runspace runspace = RunspaceFactory.CreateRunspace();
runspace.Open();

RunspaceInvoke runSpaceInvoker = new RunspaceInvoke(runspace);
runSpaceInvoker.Invoke("Set-ExecutionPolicy Unrestricted");

// create a pipeline and feed it the script text (AddScript method) or use the filePath (Add method)
Pipeline pipeline = runspace.CreatePipeline();
Command command = new Command(SCRIPT_PATH);
command.Parameters.Add("", ""); // I don't have named paremeters
pipeline.Commands.Add(command);

pipeline.Invoke();
runspace.Close();