plead vs request

plead

verb
  • To beg, beseech, or implore. 

  • To present (an argument or a plea), especially in a legal case. 

  • To offer by way of excuse. 

  • To discuss by arguments. 

request

verb
  • To ask for (something). 

  • To ask (somebody) to do something. 

noun
  • A message sent over a network to a server. 

  • Act of requesting (with the adposition at in the presence of possessives, and on in their absence). 

  • Condition of being sought after. 

  • A formal message requesting something. 

How often have the words plead and request occurred in a corpus of books? (source: Google Ngram Viewer )