Semicolon and line break in CSV download via PHP code

We have a Wordpress plugin with PHP code to download some text field. One of the text fields (text area) can also contain semicolons and linebreaks. Now the semicolon separates the content into different fields and the line break creates a new record (next line). Instead, all contend (including semicolons and line breaks) shall remain in the same field. So text editors (EditPad Lite, Editor or Wordpad) as well as Excel shall not interpret the semicolon inside the text area as separator, but as content. How can this be achieved? To complete this project, we just need the regarding code, so our developer can adopt it and the download needs to show semicolons and line breaks as part of the content of the same field.